Thanks! Much easier to read
I think we are mostly in agreement, overall. Possibly preferences can account for the difference. Also, I've read about the DT1350s sounding different from earlier releases to current ones. Not sure if that's true or not but just raising it as a possibility.
I agree that bass extension goes to the 1350 which I like. I feel the Amperior has more texture in the bass, but they both do bass really well. I tend to prefer the more neutral 1350 bass to the exaggerated Amperiors.
As to your question about the 1350s highs, they are not lacking or dark. I can't stand the dark sound, so I have to say the 1350s highs are just fine and extended but miss that sparkle. The area where I find missing information is the upper midrange and lower treble. In a vacuum, the 1350s sound great. It was only when I compared it to the Amperior that I realized there was a subdued nature which might account for the timbre difference.
One critical point that favors the Amperior is that they are easy to drive, so they can be amped or used straight out of the phone. While I wouldn't bother listening to the 1350s out of the phone. I really only appreciated them with when amped properly.